Personal communications is on the brink of an unprecedented expansion of its capabilities. With the advent of advanced personal communications services, such as cellular telephone and low earth orbit (LEO) satellite services, this expansion of capabilities benefits mobile users. Not only does the expansion of capabilities benefit voice communications, but it also benefits data communications, such as might be used with portable computers and other personal data communicators.
A major difficulty with the expansion of services is that a wide variety of different voice and data communications protocols have been proposed. It can be expected that this variety will increase, both world-wide and within a local area. For example, each communications service has its own technical, geographic and feature sets. Technical parameters include frequency(ies), modulation and protocol used, among others. Geographic parameters are dictated by the particular locale, such as footprint. Feature sets describe whether the service is voice, paging, data, or some combination of these.
As a consequence, a given communications device will become less useful as its user attempts to utilize it in areas that have incompatible services. For example, as people who rely on mobile communications move through a day, they can move in and out of different coverage areas and their communications needs will change constantly. Further, even within a local area, a given communications device will gradually become less useful as its built-in capabilities are rendered out-of-date by newer services.
It is clearly undesirable for the individual to have to carry a different communication device for each communication service. Also, few individuals really want to know the details and peculiarities of each of the available communication service. Most individuals would much rather have seamless service that is simple, convenient and cost-effective.
Therefore, it is advantageous to have a single personal communications device that will reconfigure itself to be compatible with whatever communication service is desired or needed. This is difficult with today's conventional technology.
Conventional technology Solutions use a combination of digital signal processing (DSP) integrated circuits and application-specific integrated circuits (ASICs). The use of a DSP in mobile applications is limited by the requirement to run on small batteries. This limits the DSP to relatively slow clock rates. If the DSP clock rate is increased, the battery life decreases rapidly. For example, when taking into account memory access, a DSP performing on the order of one hundred operations per sample on a megahertz range signal can require a clock rate in the gigahertz range. This can consume all the power in small portable batteries in unacceptably brief times.
There are presently approximately two dozen non-compatible wireless communications services, and the number is currently increasing rapidly. There are also about twelve wired communications services, of which approximately eight are widely used today. The number of services, particularly wireless ones, will continue to increase over the next several decades because technology is evolving rapidly.
Conventional technology approaches use a combination of analog processing and ASICs to process these high frequency signals. These approaches work well for single service portable devices but do not perform well with multiple services, especially in portable units. When applied to multiple services, the conventional approach results in the use of multiple ASIC chip sets and analog subsystems. It quite often results in the use of multiple DSPs as well. The result of using conventional technology approaches is a large, heavy, expensive portable unit having short battery life and a range of supported services which is stagnant. In fixed units the problems of battery life are diminished, but the problems with stagnant service growth are magnified.